Crime scene evidence such as that collected on sample swabs often provides critical information necessary for identification of suspects and the determination of guilt or innocence of accused individuals at trial. Often, the evidence is in the form of body fluids such as blood, semen, saliva, urine, etc. Care must be taken to ensure that the sample collected is: representative of the evidence present at the crime scene (i.e., it is related to the crime); labelled properly and appropriately (i.e., with the case number, type of specimen, etc.); and that the sample is transported properly and in a timely manner to the crime laboratory. In addition, care must be taken to avoid contamination of the sample with extraneous material. This is particularly important in cases where DNA testing will be conducted on the sample.
Decay of biological samples by bacteria and other microorganisms, as well as other environmental conditions (e.g., heat or high temperatures) must be avoided in order to ensure that the collected sample will provide the necessarily reliable answers upon analysis. For example, it is known that DNA is rapidly degraded in moist, warm conditions, with most of the DNA in tissue specimens degrading within days or even hours. However, DNA is extremely stable under certain environmental conditions. Acceptable DNA analyses may be performed on dried blood and semen stains collected many weeks prior to the analysis (See e.g., S. Easteal el aL, DNA Profiling Principles, Pitfalls and Potential, Harwood Academic Publishers, Philadelphia, at p. 68, 1991!). In addition to DNA analyses, other types of biological sample analysis is routinely conducted on dried samples, including serological (i.e., electrophoretic or immunologic) methods to identify antigens and/or proteins present in the samples. Thus, rapid and thorough drying of samples is routinely encouraged in the collection and handling of forensic samples (See e.g., S. Easteal el al., supra, at pages 141-142; and S. H. James, "The Documentation, Collection, and Evaluation of Bloodstain Evidence," in W. G. Eckert and S. H. James, Interpretation of Bloodstain Evidence at Crime Scenes, Elsevier, New York, at pages 87-113 1989!).
However, it is often very cumbersome to dry samples on site at crime scenes. The use of forced air (e.g., fans, or cold hair dryers), or air drying the samples, presents problems. For example, fans and hair dryers must be included in the crime laboratory's equipment pack, and they usually require an electrical source in order to work. In addition, it is important not to use heat to dry the samples, as the high temperatures may degrade the samples. Furthermore, if trace evidence is involved, fans are not recommended, especially if more than one item is being dried at the same time, as cross-contamination must be avoided (See, J. M. Rynearson and W. J. Chisum, Evidence and Crime Scene Reconstruction, National Crime Investigation and Training, pages 57-62 1983!). Thus, although forced air methods may provide advantages in terms of speed, other considerations, such as the availability of the needed equipment, and the risk of cross-contamination must be kept in mind. Although air drying avoids the need for equipment such as fans and hair dryers, it is often impractical, as time is required for the sample to dry adequately. In addition, if the sample is left exposed to the air without any type of protection, the chances of sample contamination increase. For example, a swab containing a blood sample that is left to dry on a countertop may become contaminated while other evidence from the crime scene is being collected, and perhaps even placed in close proximity with the drying swab. These factors are important in court as such opportunities for contamination may provide the doubt necessary for an acquittal of the suspect in the case.
Although drying of samples at the crime scene is preferred, it may not be accomplished. This leads to problems associated with the transport of wet samples to the crime laboratory. For example, criminalists and crime scene technicians often place inadequately dried samples into paper envelopes or bags, or wrap them in index cards for transport (See e.g., U.S. Pat. No. 5,025,920, to Walsh et al.). The paper allows the sample to leak through the envelope or bag, contaminating the environment surrounding the sample, and reducing the volume of the sample available for testing. If many samples are placed close together, the potential for cross-contamination of the samples is present. Thus, the reliability of all of the samples in the collection may become questionable, a factor the defense attorney will highlight during the trial of the accused suspect.
Double bagging of the sample by use of a rolled up index card to protect the sample, and then placing the card in a second evidence container, such as an envelope, may help avoid the problems of contamination of the environment with wet samples. However, time must be taken to carefully staple the moist swab to the index card, label the card in a location where the sample will not contact the ink or pencil markings (i.e., to prevent the sample from rendering the label unreadable), roll the card, and then staple the card in a manner such that the card completely surrounds the sample except at the end (i.e., the card resembles the shape of a bullhorn, with the sample stapled to the inside of the horn). Another problem is presented by the cards in that they are easily crushed during transport of the sample. In addition, because the wet sample is in contact with the card, the sample may be allowed to leak through the card, leading to the same concerns as discussed above. Furthermore, this system is not designed to facilitate the drying of the sample at a rapid rate.
Plastic transport bags do not provide the answer to the prevention of sample contamination. Although the plastic bag will help to prevent contamination of the sample due to materials falling or dropping on to the sample. Placing a wet sample in a plastic bag creates an ideal environment for bacterial and fungal growth, as the moistness is retained within the bag and often the temperature is optimal for microbial growth. This leads to the degradation of the sample, again decreasing its reliability and value.
Although the use of medical sampling and transport devices might, at first appear to provide the answer, the medical situation is diametrically opposed to that of forensics. Swabs for medical testing and analysis are often collected and transported in plastic or other containers (See e.g., U.S. Pat. No. 4,749,655, to Monthony, U.S. Pat. No. 5,163,441, to Monthony, U.S. Pat. No. 4,136,680, to Southworth, U.S. Pat. No. 2,835,246 to Boetter, U.S. Pat. No. 3,513,830, to Kalayjian, U.S. Pat. No. 4,457,313, to Alter, etc.). However, these devices and methods are intended to protect the microorganisms present on the swab, while preventing contamination of the sample and environment. Thus, the swabs are often placed into media which protect the microorganisms from drying or other environmental stresses. Indeed, specialized transport media have been developed for such uses (See e.g., R. M. Atlas, Handbook of Microbiological Media, CRC Press, Boca Raton, pages 67-68, 179, 190, 193, 510, 653-654, 764, 836, 854-855, 920-922, 978, and 985 1993!).
What is needed in the art is a means to transport forensic samples to the laboratory in a manner that encourages the sample to dry, as well as protect it and the environment from contamination, and avoid the loss of sample to leakage or other factors.